The present invention relates to a cooling unit used in an air conditioning apparatus for a vehicle in which an engine serving as a drive source for a compressor is temporarily stopped when the vehicle is stopped.
In the present specification and appended claims, the upper and lower sides of FIGS. 1 and 3 will be referred to as “upper” and “lower,” respectively.
Also, in the present specification and appended claims, the term “condenser” encompasses not only an ordinary condenser but also a sub-cooling condenser having a condensing section and a subcooling section.
In recent years, in order to protect the environment and improve fuel consumption of automobiles, there has been proposed an automobile designed to automatically stop the engine when the automobile stops, for example, so as to wait for a traffic light to change.
However, an ordinary air conditioning apparatus has a problem in that, when the engine of a vehicle in which the air conditioning apparatus is mounted is stopped, a compressor driven by the engine stops, and supply of refrigerant to an evaporator stops, whereby the cooling capacity of the air conditioning apparatus sharply drops.
One conceivable measure for solving such a problem is imparting a cool storage function to the evaporator, to thereby enable cooling of a vehicle compartment by releasing the cool stored in the evaporator, when the compressor stops as a result of stoppage of the engine.
Such an evaporator with a cool storage function has been proposed (see Japanese Patent No. 4043776). The proposed evaporator includes upper and lower header tanks spaced from each other in the vertical direction, and a heat exchange core section provided between the two header tanks. The heat exchange core section includes a plurality of flat refrigerant flow tubes which are disposed such that they are spaced from one another in the longitudinal direction of the two header tank, their width direction coincides with an air-passing direction, and their longitudinal direction coincides with the vertical direction. Upper and lower end portions of the refrigerant flow tubes communicate with the upper and lower header tanks, respectively. The heat exchange core section also includes cool storage material containers which are disposed in at least some of a plurality of air-passing clearances, each formed between adjacent refrigerant flow tubes, such that their width direction coincides with the air-passing direction, and their longitudinal direction coincides with the vertical direction. The cool storage material containers are filled with a cool storage material. The cool storage material within the cool storage material containers is cooled by the cool carried by the refrigerant flowing through the refrigerant flow tubes. As in the case of an ordinary evaporator, the evaporator with a cool storage function disclosed in the patent publication is used as a cooling unit of an air conditioning apparatus for a vehicle in a state in which the lower header tank is fitted into a drain case which receives condensed water generated on the evaporator (see, for example, Japanese Patent No. 3287100).
An air conditioning apparatus for a vehicle which includes an evaporator with a cool storage function disclosed in Japanese Patent No. 4043776 operates as follows. In an ordinary cooling period in which a compressor is operating, the cool carried by the refrigerant flowing through the refrigerant flow tubes is transferred to the cool storage material within the cool storage material containers, and is stored in the cool storage material. When the compressor stops, the cool stored in the cool storage material within the cool storage material containers is released to air passing through the heat exchange core section via the refrigerant flow tubes with which the cool storage material containers are thermally contacted.
Incidentally, the air conditioning apparatus for a vehicle which includes an evaporator with a cool storage function disclosed in Japanese Patent No. 4043776 has been recently required to more effectively reduce a drop in cooling performance at the time when the compressor stops.
In order to meet such a demand, the present applicant has proposed an evaporator with a cool storage function which can more effectively reduce a drop in cooling performance at the time when the compressor stops. Specifically, the present applicant has proposed an evaporator with a cool storage function as disclosed in Japanese Patent No. 4043776 wherein each of the cool storage material containers has a container main body portion joined to corresponding refrigerant flow tubes, and an outward projecting portion which is provided such that it extends from the leeward side edge portion of the container main body portion and projects from the refrigerant flow tubes toward the leeward side (see Japanese Patent Application Laid-Open (kokai) No. 2010-203748).
However, when the evaporator with a cool storage function disclosed in the Japanese Patent Application Laid-Open No. 2010-203748 is used as a cooling unit of an air conditioning apparatus for a vehicle, a problem arises. Specifically, even when the lower header tank of the evaporator is fitted into a drain case for receiving condensed water, the drain case may fail to efficiently drain condensed water generated on the outward projecting portions of the cool storage material containers.